MTN ******** contract renewals and migration without customer approval

The service provider extends/ migrates contracts without customers permissions and when it’s time to reverse the migration it’s a whole new story. It’s been more than 4 months now that I’ve been fighting this battle and they keep changing their stories. I have been charged over R2000 over and above what I’m supposed to be paying monthly. I have visited the MTN store, called more than 20 times with no joy. It is super frustrating and unimaginably stressful!!